In many industries it is necessary or desirable to measure the torque required to rotate one of two relatively rotatable components relative to the other of said components for various purposes, e.g., for quality control. Thus, for example, precision bearings, electric and air motors, hydraulic and pneumatic pumps, magnetic tape and disk drives, and control knobs for electronic and mechanical apparatus are commonly required to have a torque resistance to rotational movement that falls within predetermined limits, and in many cases it is essential that the torque measuring system be able to rapidly and reliably provide a pass/fail indication in lieu of or in addition to an indication or measurement of torque value. Similarly in industries involving the manufacture and/or filling of containers having screw-type closures, e.g., flexible or inflatable tubes or bottles used to contain commodities such as toothpastes, shampoos, lotions, adhesives and oils, etc., having reliable means for measuring the torque required to unscrew such caps is desirable to make certain that caps are screwed on tight enough so as not to leak, but also not so hard as to make them difficult to unscrew using only hand action.
Heretofore, many different types of torque measuring devices and systems have been produced for various applications. Such different torque-measuring systems range from those that incorporate or use (a) mechanical dial type torque gages and torque sense-slip clutch mechanisms, as shown, for example, by U.S. Pat. Nos. 4,539,852 and 4,716,772, (b) strain gages as shown by U.S. Pat. Nos. 4,023,404 and 4,811,850, (c) torque sensors producing a digital electronic readout as shown by U.S. Pat. No. 4,794,801, and (d) pneumatic torque-sensing gages as disclosed by U.S. Pat. Nos. 3,866,463 and 4,696,144. See also U.S. Pat. No. 3,495,452, issued Feb. 17, 1970 to C. E. Johnson, Jr. et al. for “Torque Meter”. Various forms of cap testers also are known, including relatively simple devices such as the ones disclosed by the following patents: (1) U.S. Pat. No. 4,539,852, issued Sep. 10, 1985 to Jerome H. Feld, (2) U.S. Pat. No. 4,716,772, issued Jan. 5, 1988 to K. B. Bubech et al., and (3) U.S. Pat. No. 4,794,801, issued Jan. 3, 1989 to T. M. Andrews et al. Relatively complex cap testers are revealed in (1) U.S. Pat. No. 3,866,643, issued Feb. 18, 1975 to D. A. Smith et al., (2) U.S. Pat. No. 4,696,144, issued Jul. 29, 1987 to G. E. Bankuty et al., (3) U.S. Pat. No. 4,811,850, issued Mar. 14, 1989 to G. E. Bankuty et al., and (4) U.S. Pat. No. 4,907,700, issued Mar. 13, 1990 to G. E. Bankuty et al.
An improved form of cap tester is disclosed by my prior U.S. Pat. No. 5,152,182, issued Oct. 6, 1992 for “Torque Measuring Apparatus”, which features the use of a torque-transmitting shaft, means for coupling the torque-transmitting shaft to one component of an article to be tested, e.g., the screw cap on a bottle, a pair of parallel flexible mechanical beams mounted in like cantilever fashion, and a force-transmitting arm having one end attached to the torque-transmitting shaft and its opposite end extending between the two beams, whereby a torque applied to the component of the article to be tested causes the torque-transmitting shaft to act via the force-transmitting arm to bend one or the other of the two beams according to the direction of rotation of the torque-transmitting shaft. An encoder translates the rotation of the torque-transmitting shaft into an electrical signal output which is used to provide a measure of the magnitude of the applied torque.